If you get over a foot of fresh anywhere over 30 degree slope that isn't regularly groomed, is known to have tree wells, is known to slide.... regardless of in or out of bounds it would be safer to have it than not.

Just don't ride around a resort in November after a 2" snow with a backpack, probe, beacon and shovel. That's stupid and I have seen it here, I told the guys they were idiots and they got upset.